Electrical conductor



Nov. 23, '1943. J. N. AKEN y 2,335,097

ELECTRICAL CONDUCTOR Filed Aug. 5, 1940 Patented Nov. 23, 1943 ELECTRICAL CONDUCTOR James N. Aken, Rome, N. Y., assigner to General Cable Corporation, New York, N. Y., a corpora'- tion of New Jersey Application August s, 1940, serial No. 350,226

19 claims. (ci. 174-121) The present invention relates to improvements in asbestos insulated electrical conductors and has for an object the provision of an improved ilameand moisture-resisting insulating compound with good electrical and physical properties. It is a further object of the invention to provide; improved insulated conductor constructions. Other objects and advantages of the invention will appear hereinafter.

Asbestos is used for electric insulation because of its ameand heat-resisting properties. However, because of its hygroscopic nature, asbestos must be saturated with a moisture-resisting comp ound in order to make it useful as electrical insulation. This saturating compound must be heatand flame-resistant in order to preserve the heatand llame-resisting properties of the asbestos.

There are a number of heat-, flameand moisture-resistant compounds which have been used heretofore to saturate asbestos insulated wires. During the past few years the electrical and physical test requirements for asbestos insulated wires have been made more strict.

The electrical tests now require that the wire, e. g., No. 16 ilexible asbestos xture wire with als asbestos insulation wrapped 14 times around a 1/2" metal mandrel and immersed in water of 40 C. for 3 hours, should have after this period a minimum A. C. resistance of 15,000 ohms. It is also required that this wire withstand 1500 volts for at least 1 minute when this voltage is applied between conductor and a tin foil Wrapped around the insulation. The physical tests now require that the insulation of the wire be flexible at C. and not drip at 100 C.

None of the previously used compounds,

ywhether based on chlorinated diphenyl or chlorinated naphthalene, were entirely satisfactory. Some were too brittle at 0 C.; others too fluid at 100 C.; others failed to meet the A. C. resistance test after 3 hours immersion.

I have discovered that if chlorinated diphenyl (M. P. 60-66 C.) is plasticized with a mixture of corn oil and polyisobutylene a compound is obtained which consistently meets all requirements. Asbestos wire saturated with this compound passes the electrical tests, is flexible at 0 C. and does notdrip at 100 C.

My tests show that neither polyisobutylene nor corn oil alone can give these improvements in a chlorinated diphenyl compound. If more corn oil` is used instead of polyisobutylene, the compound is too fluid at 100 C. Also the wire fails on the 40 C. insulation resistance test because the compound is too fluid at that temperature and does not have the moisture resistance obtained with the chlorinated-diphenyl compound prepared with a mixtureof cornoil and polyisobutylene. Using only polyisobutylene and no corn oil in the chlorinated diphenyl results in a wire which will pass the C. drip test and the 40 C. insulation resistanceptest, but will fail on the 0 C. flexibility test. Also this compound would be too viscous to saturate asbestos at about C., the temperature fusedl to saturate the asbestos insulation of this wire duringlits manufacture. The use of a combination of polyisobutylene andcorn oil gives improved physical and electrical properties which cannot be obtained by the use of only one ol'. these compounds, or by the use of any other plasticizer or combination of plasticizers of which I am aware;

A preferred example of the composition is as follows: f i I I f `Pounds Chlorlnated diphenyl (M. P. 60-66 C.),.' 70 Parain M.\P. 52 C.) 10 Polyisobutylene (mol. wt. 10,000-20,000) v 10 Corn oil 10 The parailln is added t0 the abovev formula for y the purpose of providing a'slippery surface ilnish Percent Chlorinated diphenyl (M. P. 60-66 C.) 60-80 Paraflin (M. P. 52 C.) at 10-20 Polyisobutylene (mol. wt. 5,000-20,000) 5-15 Corn oil y5--15 The polyisobutyleney 'preferred in these com-f positions has a molecular weight of 10,000 to.` 20,000, but polyisobutylene with lower molecular weight may be used. Corn oil is the preferred ,1

oil, but other saponiable oils with similarr physical and chemical properties may be usedf such as cottonseed and peanut oil: Very viscous oils like castor oil could not be used because due to the higher congeal'ingY temperature" of this oil, compounds made with it would not be suiciently f flexible at 0 C.

Qn most asbestos wire constructions the as- .f i

bestos is applied in two or more'layers. The

above compounds are eminently suitable for the saturation of the first or inner layer, although at times for the second or outer layer a slightly harder and "drer (less tacky) finish may be desirable. I'his can be obtained, for example, by adding 10-30 parts by weight, but, preferably not over 25 parts by weight, of a pigment to the above compound. l

As an example, for a white finished wire the following compound may be used on the outer asbestos layer:

Pounds Chlorinated diphenyl (M. P. 60-66" C.) '70 Parafiin (M. P. 52 C.) 10 vPolyisobutylene (mol. wt. 10,000-20,000) 10 Corn oil, refined 10 Titanium dioxide 15 The use of a pigmented compound in the outside asbestos layer over a softer saturant in the inner asbestos layer has several advantages. First, by using pigments of different colors, wires with different colors can be made for polarity identification.- Second, the pigmented outer saturant acts as a seal to prevent, even at temperatures over 100 C., the migration of the inner saturant if the latter has been applied in excess.

The accompanying drawing illustrates diagrammatically a single conductor construction embodying the novel features of the invention.

The legends applied to the drawing are by way` of illustration and not limitation.

As illustrated in the drawing, the conductor I0, which may be of any suitable type and material common in the art, may be covered with a separator II of paper or Cellophane, or if desired, the separator may be omitted. Overlying the conductor or the separator, as the case may be, is an insulating jacket I2 of asbestos, which may be felt, roving, tape, or braid, as desired, which insulating layer is saturated by the.heat-, flameand moisture-resistant compound I3 described above. A second insulating jacket I4 of felted, roving, taped or braided asbestos may be applied over the saturated layer I2, ii desired, and this layer may be treated in turn with the protective compound I5 according to this invention.

f The manner of manufacturing the cable will be apparent to those skilled in the art in View of the above description of the invention.

Advantages of the invention reside in the provision of an insulated conductor which possesses all of the necessary characteristics of heat resistance, fiameproofness, waterproofness, dielectric strength, insulation resistance, pliability at 0 C., andv drip-proof at 100 C. While the chlorinated diphenyl-wax-polyisobutylene-corn oil composition of the invention is particularly useful as a saturant for asbestos insulation, it is also useful with beneficial results on other fibrous materials.

I am aware that chlorinated diphenyl has previously been proposed as a moisture and flame resistant saturant for asbestos insulation and the like, but so far as I am aware, chlorinated diphenyl has not previously been compounded with the plasticizing and fluxng ingredients as in my invention, or so as to provide a saturant for asbestos insulated wire of the properties above described.

While certain preferred embodiments of the invention have been described by way of illustration, it is to be understood that the invention is not to be so limited as it may have Various other modifications within the limits of the prior art and the scope of the subjoined claims.

I claim:

1. An insulated electrical conductor comprising a conductor core, an asbestos insulation therefor, said insulation being saturated with a compound comprising chlorinated diphenyl and paraffin wax plasticized with a mixture of polyisobutylene of 10,000 to 20,000 molecular Weight and com oil, the polyisobutylene and the corn oil each representing not less than about 5% of the compound by weight.

2. An insulated electrical conductor comprising a conductor core, an asbestos insulation therefor, said insulation being saturated with a compound comprising chlorinated diphenyl, petroleum wax, polyisobutylene of 5,000 to 20,000 molecular weight and corn oil, said saturated asbestos being ameand moisture-resistant, resistant to iiow at C. and flexible without cracking at 0j C.

3. An insulated electrical conductor comprising av conductor core, an asbestos insulation therefor, said insulation being saturated with a compound comprising chlorinated diphenyl, paraiiin and a coloring pigment plasticized with a mixture of polyisobutylene of 10,000 to 20,000 molecular weight and corn oil, the polyisobutylene and the corn oil each representing not less than about 5% of the compound by weight.

4. An insulated electrical conductor comprising a core, an asbestos insulation therefor, said insulation being saturated with a compound comprising chlorinated diphenyl plasticized with a mixture of polyisobutylene of 5,000 to 20,000 molecular weight and corn oil, a second asbestos layer thereover, said second layer being saturated with a compound comprising chlorinated diphenyl, paraiin wax and a coloring pigment plasticized with a mixture of polyisobutylene of 10,000 to 20,000 molecular weight and corn oil, the polyisobutylene and the corn oilin the compound saturating the said second layer each representing not less than about 5% of the compound by weight.

5. An insulated electrical conductor comprising a conductor core, an asbestos insulation therefor, said insulation being saturated 'with a compound comprising chlorinated diphenyl plasticized with a mixture of polyisobutylene and corn oil, the polyisobutylene and the corn oil each representing not less than about 5% of the compound by weight.

6. An insulated electrical conductor comprising a conductor core, fibrous insulation therefor, said insulation being saturated with a compound comprising chlorinated diphenyl and paraffin wax plasticized with a mixture of polyisobutylene of 5,000 to 20,000 molecular weight and corn oil, the polyisobutylene and the corn oil each representing not less than about 5% of the compound by weight.

7. An insulated electrical conductor comprising a conductor core, fibrous insulation therefor, said insulation being saturated with a compound comprising chlorinated diphenyl plasticized with a mixture of polyisobutylene and corn oil, the polyisobutylene and the corn oil each representing not less than about 5% of the compound by weight.

8. A ameand moisture-resistant saturant having good electrical insulating properties comprising chlorinated diphenyl and paraiiin plasticized with a mixture of polyisobutylene of 10,000 to 20,000 molecular weight and corn oil, the polyisobutylene and the corn oil each represcnting not less than about of the saturant by weight.

9. A iameand moisture-resistant saturant having good electrical insulating properties comprising clilcrinated diphenyl and paraffin plasticizecl with a mixture of polyisobutylene and coin oil, the chlorinated diphenyl representing not less than about 60% of the saturant by weight and the polyisobutylcne and the corn oil each representing not less than about 5% of the compound by Weight,

10. A flamcand moisture-resistant saturant having good electrical insulating properties comuising chlorinated diphenyl plasticized with a mixture of polyisobutylcne and corn oil, the polyisobutylcne and the corn oil each representing not less than about 5% of the saturant by Weight.

1i. A flameand moisture-resistant saturant having good electrical insulating properties and consisting substantially of:

Pounds chlorinated diphenyl (M. P. 60-65" C.) 70 Parafiin wax (M. P. 52 C.) 10 Polyisobuiylene tniol. wt. 10,000-20,000) Corn oil 10 l2. A ameand moisture-resistant saturant having good electrical insulating properties comprising:

Per cent Chlorinated diphenyl (M. P, 60-66" C.) 60-80 Parafn 1M. P. 52 C.) 10-20 Polyisobutylene nmol. wt. 500G-20000)--- 5-15 Corn oil 5-15 13. A amcand moisture-resistant saturant having good electrical insulating properties comprising:

Per cent Chlorinated diphenyl (M. P. 60-66" C.) 60-80 Parafn (M. P. 52 C.) 10-20 Polyisobutylene (mol. Wt. 5,000-20,000) 5-15 Corn oil 5-15 Pigment 10-25 14. A compound comprising chlorinated diphenyl and a plasticizer comprising a mixture of polyisobutylene of 5,000 to 20,000 molecular weight and corn oil, there being from about onethird to about three times as much polyisobutylene as corn oil.

15. A compound comprising chlorinated dip-henyl and a plasticizer comprising a mixture of approximately equal parts of polyisobutylene of 5,000 to 20,000 molecular weight and corn oil.

16. An insulated electrical conductor comprising a conductor core, a brous insulation therefor, said insulation being saturated with a cornpound comprising:

Per cent Chlorinated diphenyl -80 Parain 10-20 Polyisobutylene 5-15 Corn oil 5-15 17. An insulated electrical conductor comprising a conductor core, a brous insulation therefor, said insulation being saturated with a. compound comprising:

Percent Chlorinated diphenyl 60-80 Paraflin 10-20 Polyisobutylene 5-15 Corn oil 5-15 Pigment 10-30 18. An insulated electrical conductor comprising a conductor core, brous insulation therefor. said insulation being saturated with a compound comprising chlorinated diphenyl plasticized with a mixture of polyisobutylene and corn oil, the chlorinated diphenyl representing not less than about 60% of the compound by Weight and the polyisobutylene and the corn oil each representing not less than about 5% of the compound by weight,

19. A arneand moisture-resistant saturant having good electrical insulating properties comprising chlorinated diphenyl plasticized with a mixture of polyisobutylene and corn oil, the chlorinated diphenyl representing not less than about 60% of the saturant by weight and the polyisobutylene and the corn oil each representing not less than about 5% of the saturant by weight.

JAMES N. AKEN. 

